Conversion of liquid hydrocarbons to fixed gases



March 29, 1955 C, BAFRANCls 2,705,193

CONVERSION OF LIQUID HYDRCARBONS T0 FIXED GASES Filed may 12. 195o 2shets-sneet 1 gw/gauw@ afm( lMarch 29, 1955 l c. B. FRANCIS 2,705,193CONVERSON 0F LIQUID HYDROCARBONS T0 FIXED GASES Filed May 12. 195o 2Sheets-Sheet 2 United States Patent O CONVERSION F LIQUID HYDROCARBUNST0 FIXED GASES Charles B. Francis, Pittsburgh, Pa. Application May 12,1950, Serial No. 161,559 4 Claims. (Cl. 48-215) This invention relatesto a method of converting liquid and liqueable carbonaceous fuels tofixed gases. The term fixed gases includes any mixture of compounds andelements that remain in the gaseous state at ordinary atmospherictemperatures and pressures. Such mixtures may be entirely consumed asfuels directly, or may be processed to obtain certain substances whichmay be used for other purposes.

More particularly, the invention relates to the conversion into ixedgases of such carbonaceous liquids as coal tar and soft pitch, which arenow largely consumed as liquid fuels, and hydrocarbon oils, such ascrude petroleum, and the residues resulting from the high temperatureprocessing thereof, which residues have heretofore been used mainly asliquid fuels in certain types of furnaces and processes operating athigh temperatures. In addition to the named liquids, the process is alsoadapted to the conversion to fixed gases of certain animal and vegetableoils, and to the conversion to fixed gases of many waste products, suchas used automobile oils, discarded wash oils, etc.

The advantages of a fixed gaseous fuel, such as natural gas, for use incertain industrial processes, as well as for household use, are wellknown. In many districts natural gas is not available. In otherdistricts, which are supplied with natural or manufactured gas,shortages are often experienced.

It is an object of the present invention to supply these deficiencieswith a fuel gas of high heating value-a fuel gas manufactured from anycarbonaceous liquid available, including such waste products as thosementioned.

Most large steel producers make coke, and in the process greatquantities of coal tar and/or soft pitch are produced and used as fuel.But the use of tar as fuel is restricted to certain furnaces, such asopen hearths, that operate at high temperatures. The tar or pitch isviscous and costly to handle, particularly in cold weather. such viscousmaterials are generally produced at a distance from the points ofconsumption and must be transported in tank cars or trucks to suchpoints.

A further object of the present invention is to provide a processwhereby the tar or pitch may be economically converted at the point ofproduction or origin into a sulfur-free fixed gas, and then delivered ingas lines (many of which are already in existence) to the points ofconsumption.

Fixed gases suitable for use as gaseous fuels have for many years beenproduced from petroleum residues. These gases are commonly designated asoil gas. In general, oil gas Varies in composition and heating valueabout as follows:

Range in Typical Analyses, Per- Oil Gas Constituents Percent By cent ByVolume ot 3 Volume specimens Methane, CH4 27.6 to 43.2. 27. 6 43. 2 30.0 Etnie, (32H5, and Propane 0.0 to 6.4...- 0. O 6.4 1.0

3 8. Eltbhylene, 02H4 and other ole- 3.5 to 17.0... 3. 5 17. 0 26.0

ns. Acetylene, 02H4 0.0 to 0.5.... 0. 0 0.5 1.1 Hydrogen, H2 50.8 to23.2.- 50.8 23. 2 9. 4 Carbon monoxide, OO 10.2 to 3.6- 10. 2 3. 6 2. 7Carbon dioxide, CO 2.6 to 1.1-... 2. 6 1.1 3.0 Oxygen, Oz 0.2 to 1.0-.0. 2 1.0 2.8 Nitrogen and otheri rt gases.. 5.1 to 4.0. 5.1 4. 0 25.0Total B. t. u. per cu. it 548 to 975.-.- 548 975 1, 030

Also,

Still a further object of the present invention is to control theheating value of a fixed gas, produced from the materials indicated, atany desired value between 500 and 1000 B. t. u. per cu. ft., and toproduce a clean vapor free gas having a heating value practicallyconstant, so that burners may be adjusted and combustion accuratelycontrolled over any desired period of time. Also, an object is toprovide for the control of the specific gravity of the gas produced inthose instances when desired.

With the exception of those processes that employ the principle ofpartial combustion of the oil with air or oxygen, and those using nickelcatalysts (which are poisoned by the sulfur in mineral oils),practically all of the processes used heretofore for converting liquidhydrocarbons into fixed gases are intermittent in operation, requiringthe use of a set of two producer units, these units consistingessentially of two or more checker chambers of brick, into one of whichoil and steam are injected while the other is being heated to restoreits temperature and eliminate carbon depositions. Such intermittentoperation is very inetcient for reasons which this specification neednot become involved.

Another object of the invention is to provide a coutinuous process thatmay be conducted in a single unit or producer, whereby gas may beproduced continuously from a given fuel oil, and at a controlled rateover long periods of time.

Still other objects will be apparent in the following specification.

In the accompanying drawings, apparatus is illustrated, in the operationof which the invention is realized, the apparatus selected in this casebeing a small unit, designed to convert about 15 gal. of oil per hourinto about 4,000 cu. ft. of gas, having a heating value of from 500 B.t. u. to 600 B. t. u. per cu. ft.:

Fig. l is a diagrammatic view,

illustrating the apparatus in longitudinal, vertical section;

Fig. 3 is another view in horizontal section of the generator unit, asseen on the plane III-III of Fig. 1;

Fig. 4 is still another view in horizontal section of the generatorunit, as seen on the plane IV-IV of Fig. 1;

Fig. 5 is a view in vertical section of a pressure-regulating electricalswitch included in the apparatus for automatically controlling thegeneration of gas according to the rate at which it is consumed; and

Fig. 6 is a developed view or layout of a vaporizer or boiler includedin the apparatus.

Referring to the drawings, the apparatus comprises a gas generator unit1, a gas-scrubbing or purifying unit 2, and a gas receiver tank 3. Thetank 3 is not essential t0 the process, and may be varied in design andsize. Indeed, it may comprise merely an enlargement in the gas main, orit may comprise a gas storage tank of any capacity desired. Thegas-scrubbing and purifying unit 2 is essential only in the event it isdesired to cool the gas, or to free it from oil and water vapors, and/orsulfur compounds.

The generator unit 1 comprises a catalyst chamber 5, constructed ofheat-resistant metal, typically chromenickel-molybdenum alloy steel.This chamber contains a porous catalyst body 6 formed of hard hematite,crushed and graded in lumps or pieces from 1/2" to 3%1 in size. Thecatalyst chamber is arranged Within a heating charnber 7. In the smallersizes of gas generators it may be practical to supply the necessary heatin chamber 7 by means of electrical resistors, but in the illustratedunit, as well as in units of larger size, the heat is preferablysupplied by burning oil and/or gas. In the present case a combinationoil-gas burner 8 s mounted on the generator body at or near the zone ofthe section plane II-II in Fig. l, and is of the construction shown inFig. 2. The burner llame parallel to a Wall of the combusfor theproducts of combustion opens through the top of the generator. Instarting with the generator cold, this burner is operated on a lightfuel oil injected with air under super-atmospheric pressure, until thegenerator is producing gas, at which time the oil is turned off and thegenerator is heated by a small portion of the gas generated, deliveredto the burner through a line 9 leading from the gas delivery line 463 ofthe apparatus.

The walls of heating chamber 7 are formed of steel plate 11, lined withrefractory material. A storage box 12 is located on top of the catalystchamber 5 and holds enough of the sized hematite to till the catalystchamber. At the bottom of the generator a catalyst-receiving box 13,formed of ordinary carbon steel, is provided.

A thermo-electric pyrometer 14 projects into the combustion chamber,and, when the generator is making gas, this pyrometer (in conjunctionwith conventional control devices, not shown) automatically controls theflow of gas to the burner, to maintain the temperature at any desiredpoint within the Working range of 1500" F. to l700 F., as revealed by anindicator 140.

Such control devices are well-known in the art and it is needless to anunderstanding of the present invention to illustrate them, or todescribe their operation in detail herein. Within the generator meansare provided to produce superheated steam, which is a gaseous oxidizingagent, for use in the production of fixed gas. Such means may comprise aboiler formed of four pairs of vertical tubes 21, 21a, 2lb, and 21C(Figs. 3 and 6), that are preferably embedded in the refractory liningof the combustion chamber, and lie within the anges of steel channels 22.that support or reinforce the steel walls 11 of the chamber 7. The twotubes of each pair are interconnected by tubes 21d adjacent their lowerends and by tubes 21e adjacent their upper ends, and the four pairs oftubes are inter-connected in series adjacent their upper ends by meansof pipes 21f. Water is supplied by a line 15 to an overhead tank 16which includes a iioat-valve 17 for maintaining the water in the tank atdesired hydrostatic head. Water from tank 16 is delivered bv way of apipe 18 to the bottom of boiler tubes 21-21f, the rate of iiow beingmeasured by iiow meter 19 and regulated by valve 20; and the steamgenerated in such tubes is delivered by way of a pipe 23 to a manifold24 that encompasses and is welded to the heat-conducting wall ofcatalyst chamber 5, in the position shown in Fig. l. In its flow in tube23 and manifold 24 the steam is highly superheated for the chemicalreactions presently to be considered. Pet cocks 51 and S2 are connectedat suitable points to the boiler tubes for testing. The describedarrangement of tubes provides a boiler that utilizes, for the generationof steam, heat which would otherwise be lost by radiation from the wallsof the generator.

From the manifold 24 steam, superheated to the temperature of the hotgases in combustion chamber 7, is jetted through orifices 2S into thecatalyst chamber 5.

Oil is injected into the porous catalyst body by means of a motor-drivenpump 26 that draws oil through line 27 from a conventional storage tank(not shown) which may be located below oor level and heated. ln the caseof very viscous fuel oils or other carbonaceous liquids that may be usedfor the production of ixed gas, the products of combustion in chamber 7may be employed to preheat such liquids. As one example of the Way thismay be done, a pipe coil 300 is shown at the top of the combustionchamber, and the viscous liquid may be passed through this pipe, wherebythe viscosity of the liquid is lowered and the temperature raised` Theliquid fuel, drawn through pipe 27 from the supply, is forced through aow meter 28` and feed line 30 to an injector pipe 29 located at anintermediate zone in the catalyst chamber, as shown. The pipe 29,otherwise closed at its inner end, is provided with a small (/32" toIAM) hole positioned in its wall to direct a jet of oil downwardly. Theinjector pipe 29 is connected to the oil feed line by a union 31, andextends through a heat resistant shield tube 32, which projects throughand is welded to the wall of the catalyst chamber 5. It is importantthat the jet of oil be directed downwardly through a small orifice. Ihave found that an injector tube with open end or large delivery orificesoon becomes clogged with carbon. It is further important that the steamshall be injected or shall be eifective below the point or points ofadmitting the oil to the catalyst.

The motor 260 that drives the pump 26 is started by closing a switch 33.Thereafter, the operation of the pump and its motor is controlled by thepressure of the gas in tank 3, through the instrumentality of a specialpressure regulating electrical switch 34, later described in detail. Bymeans of said switch 34, which maybe set to respond to a pressurebetween one-half lb. and two lbs. in tank 3, the energizing circuit ofthe pump motor 260 is interrupted when the pressure in tank 3 reachesthat at which said pressure-regulating switch is set. The circuit isreclosed when the pressure in the tank drops below that at which suchswitch is set. In this way the generation of gas is automaticallycontrolled and adjusted to the rate at which the gas is used, up to'themaximum capacity of the generator. The tioat-valve in tank 16 and thevalve 20 control the ilow of water 4to the generator, and these valves,in conjunction with the gaspressure-controlled oil pump 26, provide foraccurate proportioning of the oil and water iiow to the generator. Otherdevices may be designed or may exist for accomplishing the same results,but they are more costly and less reliable than the device 34. Forexample, if a water pump and an oil pump were driven by a single motorythat stops the ow of both oil and water at the same time, the resultswould be imperfect, since the ow of the water should be maintained forseveral minutes after the oil is shut off, to prevent the formation ofcoke carbon, and to permit the regeneration of the catalyst in chamber5.

In preparing the apparatus for service, the catalyst chamber 5 andstorage box 12 are lled with the crushed and sized hard hematite, andgasketed covers 35 and 35a are securely bolted in place over thecharging openings in the top of storage box 12. The generator isgradually heated to a temperature of l650 F., as shown by the indicator140.

While the generator is being heated, the gas scrubbing and purifyingunits are preparedA `for use. The scrubbing and purifying units includea cooler and scrubber unit 36, an oil separator 37, a sulfur remover 45(employed only where the removal of sulfur is needed), and an oilscrubber 46. The scrubber 36 and the oil separator 37 are charged withcold water by opening a valve 38 in a pipe leading from the water supplyline 15.

The scrubber 36 comprises a vertical steel tank, having a pipe 360extending from a point midway of its vertical extent downwardly to theoil separator 37, which also comprises a vertical tank, arranged atlower level than tank 36. When the rising level of the water in tank 36reaches the mouth of pipe 360, water ows through such pipe into the oilseparator 37, and when the level of the water rising in the oilseparator reaches the point where it appears in a sight gage 39, thewater inlet valve 38 is closed. Next, if sulfur-free gas is desired, afew pounds of slaked lime are introduced through cover 40 of a sealedcontainer 42, the lime being placed and supported upon a perforatepartition or screen 41. The cover 40 is then sealed in place on the topof container 42, and a valve 43 is opened to admit water from supplyline 15. The water rises through the body of lime on screen 41 until itslevel reaches the opening of a pipe 420 leading from container 42 to the.top of the sulfur remover 45.

The sulfur remover 45 comprises a vertical tank having a water-overflowpipe 450 leading into the oil separator tank 37. As the water rising intank 45 reaches the mouth of pipe 450, it overows through the latterpipe into the oil separator tank 37, with the effect ,that the level ofthe water in sight gage 39 begins to rise. At this time the valve 43 isadjusted in a position which (in the case of the 5000 C. F. H. apparatusherein illustrated) reduces the low to about one quart per minute. Therate of ow is determined by opening valve 44 in a line 440 leading fromthe bottom of the oil separator 37 and measuring the water delivered.The valve 43 is manipulated until it reaches the position at which theow through pipe 440 reaches the desired rate. The water running frompipe 440 may be led to a drain line, sewer, or other convenient point ofdisposal. When the desired flow of water has thus been establishedthrough the lime container 42, the tank 45, the tank 37, and drain line440, the valve 38 is reopened and adjusted in such position that thetotal ow of water from drain line 440 equals about one gallon per minutewhen the water is at 40 F., or one and one-half gallons per minute whenit is at 65 F. The level of the water is thus established at operatinglevels in scrubber 36, sulfur remover 45, time container 42, and oilseparator 37. Then, the positions in which the valves 38 and 43 havebeen adjusted are marked and the valves closed.

aromas The oil scrubber 46 is now made ready. The oil scrubber consistsin a vertical tank having two horizontal partitions 460 and 461, asshown. The chamber 470 above partition 460 includes a bubbler cap 67,whose lower edge is notched, as shown. The cap 67 seats over the upperend of a tube 68 which extends downwardly through the partition 460 to abubbler cap 69 at the bottom of the tank. In preparing the oil scrubberfor service, light oil (such as No. 1 or No. 2 fuel oil) is introducedto the upper chamber 47 by way of a funnel inlet 48 including a valve480. From the chamber 47 the oil runs into chamber 470 by way of -aby-pass 490 that includes a valve 49. The oil rises in chamber 470 tothe level at which it overflows the upper edge of tube 68, whence itfalls .through such tube to the bottom of tank 46, where it forms a bodyof oil that envelopes the bubbler cap 69. When adequate pools of oilhave thus been formed around the bubbler caps 67 and 69, the valve 49 isclosed and the chamber 47 is filled, whereupon the pouring of oil intothe funnel 48 is discontinued and the valve 480 closed. Next, the valve49 is opened, and is adjusted in such position that the oil ows throughby-pass 490 at a rate of about sixty drops per minute, asmay be checkedby means of a sight-glass 50 included in the bypass. A vent tube 471opens through the partition 461 and extends almost to the top of chamber47. The oil is fed at the rate of about sixty drops per minute as longas the generator remains in operation.

While the scrubbing and purifying units are being brought into servicecondition as described above, the ring of the combustion chamber iscontinued, until the temperature therein reaches 800 F. or 900 F. Then,the pet cock 51 and valve 20 are opened, admitting water into the boiler21-21f. When water flows from said pet cock, the pet cock and valve 20are closed and pet cock 52 opened. Pet cock 52 remains open until thetemperature in the combustion chamber 7 reaches 1650" F., at which timepet cock 52 is closed, and valve 20 is adjusted to provide for a ow ofwater at a volumetric rate equal to one-half that of the oil deliveredby pump 26 for conversion to gas.

In the particular case of the generator illustrated and described hereinthe water ow may be at a rate of one pint per minute. Next, any excesswater in the scrubbers is displaced and the apparatus tested for leaks,by admit- `ting compressed air into line 57 through an inlet 570 untilthe pressure in tank 3 rises to two lbs. The specied ow of cooling andscrubbing water is then established by opening and adjusting valves 38,43 and 44, the

valves 38 and 43 being opened at the marked positions o alreadydetermined for the required flow.

To start the production of gas, main delivery valve 53 is opened, switch33 is closed to start the oil pump, and valve 54 is opened until the owmeter 28 indicates the ow of oil desired-one quart per minute for theillustrated generator. Gas is formed at once and soon displaces all theair in the apparatus. With the catalyst chamber filled with freshlyprepared hematite, the gas is high in CO2 and N2 for the first five toten minutes, and this gas may be wasted by temporarily closing valve 53and opening pet cock 530. The gas released through pet cock 530 may beburned. After about ten minutes the pet cock 530 is closed and maindelivery valve 53 is opened, allowing the gas to flow to the desiredpoints of consumption.

The conversion of the oil to gas is effected within a fraction of secondby a series of physical and chemical reactions. For example, when No. 2fuel oil is injected (as at 29) into the hot hematite it is rstvolatilized and then decomposed by the process known as cracking tolighter or more volatile compounds and carbon. The carbon is no soonerformed than it reacts either with the ore or the superheated steaminjected (as at 25) to form CO gas or CO and H2 gas according to thefollowing type reactions:

Reaction a occurs only when the catalyst is new. fThe surfaces of thepieces of hematite (FezOa) that form the catalyst are soon reduced tomagnette (Fes04) whereupon only reaction b can occur, such reaction btaking place only on the surfaces of the pieces of ore. These changesand reactions give a mixture of fixed gases composed of CO and H2, plusvapors composed of water and light oils. As these mixtures ascendthrough the hot ore body above, some of the light oils undergo, whilepassing through super-heated tubes 55 and 55a, a pyrolysis which resultsmainly in the formation of unsaturated hydrocarbons known as olens,while others of the light oils react with the ore and water to form CH4,H2 and CO. If the gas is not cooled quickly, the oletins tend topolymerize, forming aromatic compounds and H2. Furthermore, if thegenerator is operated at maximum capacity, and particularly attemperatures near 1500 F., a little oil vapor escapes unchanged with thegas passing through the super-heater tubes 55 and 55a at a highvelocity.

In chamber 5 the gases, together with some water and oil vapors, leavethe ore body at a temperature between 1300 F. and 1500 F., and passthrough a duct 57 into the cooler and scrubber 36. At the top of thisscrubber cold water, entering a manifold 58, is sprayed through orifices580 into the gas, thereby cooling it. The gas flows downwardly through atube 59 into a distributing or bubbler cap 60, from the bottom of whichthe gas rises and bubbles through a colum 600 of water extending to aheight slightly above the bottom edge of the mouth of overow pipe 360.By this scrubbing action, most of the water and oil vapors arecondensed, and, the oil in globule form escapes with the cooling waterthrough the overllow 360. In this scrubber 36 some sulfur and otherwater-soluble compounds are separated from the gas. The temperature ofthe overflow water from this scrubber is kept below 120 F. If thetemperature rises above this value the flow of water is increased byadjusting valve 38. If, in order to keep the temperature of the waterdown to desired value, the ow is increased to a rate at which the waterlevel rises above the gage glass 62, drain valve 63 at the bottom of thescrubber is opened until the water reaches the normal level, whereuponvalve 63 is closed and the flow through valve 44 re-adjusted.Cleanliness of the gas is tested by opening a pet cock 64 provided atthe top of scrubber 36. The escaping gas is ignited and a flame keptburning with a long candle-like llame.

The gas leaving the scrubber 36 at a temperature of from 100 F. to 120F. carries with it some entrained water and oil, some fog, and part ofthe sulfur in the gas developed in the generator, mainly in the form ofHzS-an acidic gas. To remove these impurities the gas is passed througha second scrubber 45, which is practically a duplicate of the iirstscrubber, but somewhat smaller in size. As the gas enters this scrubberby way of a duct 361 it is scrubbed with dilute lime water obtained fromtank 42, the lime water being introduced through a spray nozzle 65 atthe top of a downtake tube 66. At the bottom of the scrubber, the gas isforced through a submerged bubbler cap 61, and as the gas temperature isnow well below F. both oil and water vapors are condensed. The limewater also removes HzS and some of the other acidic gases present, suchas CO2. The lime water may be very dilute, as water having a hydrogenion concentration of pH 8 is effective in removing 90% of the H2S in thegas, assuming of course that sufficient lime water is supplied.

The gas produced from certain oils contains some organic compounds ofhigh molecular weight in molecular suspension which are not removed byscrubbing the gas with water or aqueous solutions. To remove thesegumlike compounds, the gas is passed from scrubber 45 through a duct 451into the double oil scrubber 46. In this scrubber the gas is forced tobubble downwardly through a body of light oil in chamber 470, whence itenters bubbler cap 67, forming a spray which is carried with the gasdown a tube 68 and into the second bubbler cap 69. The gas bubblesupwardly through the body of oil in the bottom of the scrubber 46,thereby separating the spray from the gas. In this way practically allof the organic compounds carried in suspension by the gas are leftbehind dissolved in the oil, which, as the process continues, rises inthe scrubber and overflows through pipe 462 into the oil-separating tank37. In this tank the ow of liquids is very slow, with the water beingremoved from the bottom by means of line 440, as already v84 that passesthrough noted. The oils, all having a density less than that of water,rise to the surface of the water in tank 37, and, by maintaining thewater level in the tank well above the water outlet the oils accumulatein the upper half of the chamber, whence they are drawn off periodicallythrough a line 59 controlled by a valve 590. The oil removed throughline 59 is returned to the oil supply tank for reintroduction to thegenerator. The process provides for practically 100% conversion of oilto gas.

The clean gas, rising from the bottom of scrubber 46, flows by way of apipe 463 into the receiver tank 3, whence it is delivered to the pointsof consumption under the control of valve 53.

From the preceding description it is apparent that the operation of thegenerator and gas cooling and purification units is practicallyautomatic as long as the rates of ow of water and oil, as adjusted atthe start of the run, are maintained. However, the amount of gas thatcan be usefully consumed by either industrial or domestic users varies,not only from day to day but also for different periods in each day,wherefore it is highly desirable to produce gas only as fast as it canbe profitably or usefully consumed. Since the proportion of oil andwater injected into the generator may vary without affecting theprocess, that is, as long as a certain minimum proportion of water isdelivered, the rate of gas production may be varied by adjusting the oilinjected. When the gas consumption for several hours is constant and canbe anticipated, a rough adjustment of the rate of iiow of water and oilcan be made by means of the ow meters provided, but such adjustment doesnot provide for the small unavoidable variations in the volume of gasconsumed in relation to the volume produced.

It is desirable that the gas be supplied at a constant gage pressure,which for most commercial uses varies from one-half lb. to two lbs. persquare inch.

To meet this requirement, a particularly effective pressureregulatingelectrical switch has been devised, the switch being shown attached togas tank 3 in Fig. l. A vertical section through the center of theswitch is shown on larger scale in Fig. 5.

The switch 34 comprises a thick-walled glass U-tube 74. The tube is of1/z" internal diameter, and is 21/2 long. measured from the inside ofthe bend in thc U. One leg of the U-tube is longer than the other, andincludes a 90 bend at its upper end, which is equipped with a rubbercollar 75 sealed and clamped in an orifice formed in the side wall oftank 3, as indicated in Fig. l. The tube is supported and protected by asteel guard 76, secured to the wall of tank 3. The longer leg of the Uis calibrated in centimeters and millimeters from a line TA6 above thebend for a distance of 5 centimeters. Clean mercury is placed in thetube to the level indicated at 90 in Fig. 5, which is the level of the25 mm. graduation on the wall of the tube.

At the top of the shorter leg of the U, a set of electric contacts 77and 81 is provided. The contact 77 comprises a ring formed of copper orbrass tubing having a diameter slightly larger than the outside diameterof the U-tube. The upper edge of the ring is swedged and ground to forma flat seat, and the body of the ring is slit longitudinally. A rubbersleeve 78 is cemented to the inner surface of the ring; an electricconductor wire 770 is solderedvto the ring; and a clamp 79 secures thering assembly in desired vertical position upon the shorter leg of theU-tube. A float 80 formed of glass tubing of l0 mm. outside diameter,closed at its lower end, tits loosely within the open end of the shorterleg of the U-tube. The length of the oat 80 is not less than 11/2, andthe otherwise open end of the float is necked-n and closed by means of astopper S3 of electric insulating material.

The contact 81 comprises a ring of light gage copper tubing, having itsupper end closed by means of copper disk 82 soldered to the edge of thering. The contact member 81 is secured to the float by means of a screwthe end wall 82 into the body of the stopper 83. The screw 84 providesthe terminal post for uniting an electrical conductor 810 to the contactmember 81. The contact member 81 normally bears at its lower edge uponthe seat formed on the upper edge of contact ring 77, as shown in Fig.5. Positionedover the assembled contact members is a protecting hood 85formed of insulating material, or of metal lined with insulatingmaterial. As long as the pressure in tank 3 remains below that desired,the oat 80 remains stationary,

with the copper rings 77 and 81 in Contact, closing through conductors8,10 and 770 that are connected to switch 33 the electric energizingcircuit of the oil pump motor 260. lf there is a drop in quantity of gasconsumed in service the pressure in tank 3 is increased, pushing themercury level in the long arm of the U-tube downwardly and raising themercury level under the oat. The tioat rises with the mercury and breaksthe circuit to the oil pump motor 260, thus interrupting the ow of oiluntil such time as more gas is consumed and the pressure in the tank'3decreased. This control is well adapted to the process, since thegenerator continues to produce some gas for several minutes after theoil is shut off, and makes gas immediately when the ow of oil into thegenerator is reinstated. This lag, or the gradual decrease in thegeneration of gas after the oil has been shut off, increases theintervals between the stopping and the starting of the motor. lt will bemanifest that, by adjusting the vertical position at which the contactassembly 77-85 is clamped on the shorter leg of the U-tube, theapparatus may be made automatically responsive to any selected deliverypressure.

The composition, specific gravity, and heating value of the. gasproduced vary somewhat according to the type of oil used, and thetemperature at which the generator is operated. With a well-conditioncatalyst in the generator operating at a temperature of l500 F., the gaswill have a specific gravity of about 0.7, and a heating value of about950 B. t. u. per cu. ft. a heating value greater than hydrogen, orcarbon monoxide, or mixtures thereof. With the generator operated at1600" F. to 16,50o F., the gas will contain a higher percentage of Hzand CO, which will lower the heating value of the gas, but will increasethe volume of gas produced from a given amount of oil. Again, byintroducing air through valve 570 the heating value of the gas may belowered to any value desired, while the specific gravity and thequantity of gas produced will be correspondingly increased, due to theformation of CO and dilution with N2. ln general, the volume of gasproduced from a given volume of oil varies from cu. ft. to 250 cu. ft.per gallon of oil, according to the type of oil used, and the heatingvalue of the gas produced.

With certain oils that give high residues on distillation, such as No. 6or Bunker C oil, it is advisable to inject a little air continuouslythrough line 57, which flows upwardly from box 13, to prevent theformation of coke in the bottom of the generator. With oils which givelittle or no residue, it is necessary to introduce only enough air inbox 13 to equal the gas pressure in the generator, and this will preventwater and oil vapors from flowing through the body of the catalyst 6into the box 13.

lf vapors are permitted to enter box 13 they will condense, creating apartial vacuum that promotes a continuation of the undesired fiow.

As already mentioned, the iron ore in acts as a catalyst to prevent theformation of carbon, and is largelyr self-regenerating, provided 'thatan excess of steam (or a little air) is employed, and the temperature ofthe ore is maintained above l300 F. in all parts of the chamber 5. Onthe other hand, if the temperature is increased above 1700 F. the oxideon the surface of the pieces of ore may bc reduced to metallic ironwhich will cause the lumps to stick together, or sinter, particularly iftoo much air is added with a high residue oil. The latter situation isavoided by limiting the operating temperature in the combustion chamber.The temperature of the ore, which is a poor conductor of heat and isbeing continuously cooled by the injected oil, is held to a valuebetween 1500" F. and 1550 F. at the top of the catalyst chamber, and toa still lower value below the point at which the oil is injected. At atemperature below l400 F. the ore will not react with carbon, and theoil will not be cracked sufficiently to form fixed gases. Ditiicultyfrom these causes is avoided by forming the catalyst chamber with itswalls flaring upwardly, as shown, and by preheating the injected steamto a vtemperature near that prevailing in the combustion chamber. Inoperating at the higher temperatures and using a high sulfur oil, theore tends to absorb some sulfur, forming FeS on the surface of thelumps, but this sulfide isreconverted to oxide by reaction with the airor Water at the high operating temperatures.

As a precaution against all factors that tend to decrease theeffectiveness of' the iron oxide catalyst, provision 1s the chamber 5made for moving the ore through the catalyst chamber j,

from the storage chamber 12 at the top of the generator to the box 13 atthe bottom. This movement is obtained by a pusher 70, which is movedback and forth through a distance of 2" to 3 by oscillating a lever 72.Each stroke of the lever pushes three to four lbs. of ore into the box13. Eight to ten strokes of the pusher each hour is suicient.

The air introduced through pipe 57 to the box 13 tends to keep thevapors from ilowing downwardly from the catalyst chamber, and serves toregenerate or reactivate the catalyst delivered into the box 13, wherebysuch catalyst may be re-used.

In the use of fuel oils giving little or no residue, movement of the oreappears to be unnecessary, especially if catalyst-regenerating air isinjected by way of box 13 to the bottom of chamber from time to time.

Regarding the overall eiiiciency of the generator; the reactions takingplace in th'e catalyst chamber are both exothermic and endothermic, withthe latter slightly overbalancing the former. The chief source of heatabsorption in the catalyst chamber is that required to vaporize the oilinjected, which, added to the heat absorbed by the chemical reactions,amounts to about 600 B. t. u. per pound of oil injected. The other heatlosses are the sensible heat in the gases formed and in the products ofcombustion that escape through the ue 73. ln large installations thelatter may be used to preheat the oil as it is pumped to the generator,and the loss from radiation may be reduced to a minimum by insulatingthe combustion chamber. Thus, the overall efficiency, by which term ismeant the total heating value of the oil used as compared with the totalheating value of the gas delivered, ranges from about 80% for the smallgenerator described herein to 85% and higher for larger units.

It will be perceived that the method of my invention involves not onlythe physical and chemical changes known as cracking, and those changesknownl as pyr0lysis, but also involves certain chemical reactions amongthe components of the carbonaceous liquid, the ore, and the water and/oroxygen of the air used. Such carbonaceous liquids as fuel oils derivedfrom petroleum are composed mainly of residues from distillation andcracking processes that are repeated until the residue will no longeryield a lighter hydrocarbon of value. a mixture of such heat-stableliquids is injected into my catalyst chamber heated to a temperatureabove l450 the initial action is that of vaporizing the oil.. Thisphysical change is instantly followed by a chemical action, in which1the hydrocarbon molecules are first broken down by reaction with oxygenderived from the oxide catalyst. Thisreaction is primarily limited tothe oxygenA available on the surfaces of the catalyst mass, and it magbe said that in some surface areas of the pieces forming catalyst massthe oxide is reduced from a higher to a lower oxide, with possibly theformation of a slightY amount of metal. With the decomposition ofhydrant carbon molecules thus initiated, there immediately follows acracking reaction, in which molecules of smaller molecular weights areformed with the usual deposition `of carbon. This carbon is converted toCO by reaction with the oxygen supplied by the catalyst, or to CO and H2by reaction with the water vapor or steam supplied. Finally, thehydrocarbons having molecular weights above ethane and butane undergo apyrolysis or decomposition without deposition of carbon, and unsaturatedhydrocarbons known as olens are formed.

In the absence of an oxidizing gas, such as water va por, the catalystoxide would soon be reduced to the point where it becomes inactive, butwith water injected in the form of superheated steam as described, thelower oxide on the surfaces of the lumps is oxidized to a higher oxide(and such slight quantity of metal as exists is oxidized), and the wateris reduced to H2. All of these reactions proceed to equilibrium, whichdepends upon the temperature and the proportion of water vapor or steaminjected.

The catalyst will be understood to be formed of a substance which yieldsor promotes the release of oxygen for breaking down heat-stablehydrocarbons as described above. In the presence of heat and such anoxidizing gas as steam, the substance of the catalyst is at leastpartially converted or restored from a lower to a higher oxide. Hardhematite, or its equivalents set forth l0 in my copending applicationfor patent, below noted, comprises such a catalyst.

Although hard hematite is preferred as the substance or material ofwhich to form the catalyst, other oxides of metals having a valency ofat least two, such as manganese dioxide, nickel oxide, and chromic,cobaltic, molybdic, and tungstic oxides, may serve. For example, I haveproduced gas using manganese dioxide as a catalyst, but I found thereduced oxide is a powder which either clogs the generator or is carriedover with the gas, making an extra step necessary to clean the gas ofthis dust. Likewise, the other oxides mentioned present certaindiculties in operation, all of which are avoided by the use of hematite.However, as those skilled in the chemical art will know, thediiiiculties referred to may be overcome by reinforcing, pelletizing, orcapsulating the catalytic substance within walls or coatings of asuitably pervious substance.

By virtue of the invention herein disclosed a clean fixed gaseous fuel,including at least one hydrocarbon gas, is produced. The gas developedin the generator is=not only cleansed of water and oil vapors in thescrubber 36, but the gas is cooled below the temperature at which thehydrocarbon gas polymerizes or decomposes under the effect of heatalone. And as already described in detail the units 45 and 46 cleansethe generated gas of acidic and gum-like organic inclusions.

In certain of the appended claims the terms oxidizing gas and gaseousoxidizing agent appear, and from the context of the foregoingspecification these terms will be understood to cover water vapor orsteam or air, or a mixture of water vapor or steam with air or oxygen.

Within the intent of the appended claims various modications andvariations in the method described may be practiced within the skills ofthe experts in the art, without departing from the spirit of theinvention.

Notice is given of my divisional application Serial No. 210,005, filedFebruary 8, 1951.

I claim:

1. The method of producing fuel gases from liquidl carbonaceoushydrocarbon mixtures, which comprises the steps of subjecting the liquidto a cracking process by injecting it at a controlled rate and at afixed point centrally located in a particulate body of hard hematitemaintained at a temperature above 1450 deg. F. and subsequentlysubjecting the products of the said cracking process to the action ofgaseous oxidizing agents simultaneously injected into the body ofhematite at points down stream from the point of injection of thecarbonaceous liquid, thereby producing a combustible mixture of iixedgases having a higher heating value than that of hydrogen, carbonmonoxide and mixtures thereof.

The method of producing fuel gases from liquid carbonaceous hydrocarbonmixtures, which comprises the steps of subjecting the liquid to acracking process by injecting it at a controlled rate and at a fixedpoint centrally located in a particulate body of hard hematitemaintained at a temperature above 1450 deg. F. and

subsequently subjecting the products of the said cracking process to theaction of gaseous oxidizing agents simultaneously injected into the bodyof hematite atpoints down stream from the point of injection of thecarbonaceous liquid, thereby producing a combustible mixture of xedgases having a higher heating value than that of hydrogen, carbonmonoxide and mixtures thereof, delivering the gaseous mixture undersuperatmosf plieric pressure into a pipe line, and regulating the rateofinjecting said carbonaceous liquid into said catalytic body inaccordance with variations in the line pressure of the mixture. j

73. The method of producing fuel gases from liquid carbonaceousmixtures, which comprises the steps of subjecting the carbonaceousliquid to a cracking process, by injecting the liquid at a controlledrate and at a fixed point centrally located in a particulate body ofhard hematite maintained at a temperature above 1450 deg. F. andsubsequently subjecting the volatile poducts of the cracking process toapyrolysis by simultaneously injecting superheated steam at pointslocated at the periphery ofthe body of hematite and down stream from thepoint of injecting the carbonaceous liquid, thereby producing acombustible mixture of fixed gases having a heating value higher thanthat of hydrogen carbon monoxide and mixtures thereof.

4. The method of producing a combustible mixture of xed gases having ahigher heating value than hydrogen, or carbon monoxide, or mixturesthereof, from a carbonaceous liquid, which method comprises subjectingsuch liquid to contact with a catalyst composed of a porous body of ironore heated to a temperature at least above the decomposition point ofliquid hydrocarbons, thereby producing hydrocarbon gases and vapors andcarbonaceous residue, and introducing superheated steam to said porousbody at points below the region where said carbonaceous liquid contactsthe catalyst and subjecting the products thus formed to the action ofsuperheated steam owing through the interstices of the ore body in thesame direction as the volatile products formed from the carbonaceousliquid, thereby converting the hydrocarbon vapors to xed gases and thecarbonaceous residue, under the combined ett'ect of said steam and saidcatalyst, to hydrogen and the oxides of carbon.

References Cited in the le of this patent UNITED STATES PATENTS1,902,004 Whitlock Mar, 21, 1933 12 Grumble et a1. Feb. 27, 1934Huettner et al. Apr. 28, 1936 Johnson June 2, 1936 Nonhebel et al. Aug.17, 1937 West Oct. 20, 1942 Rollman et al. Jan. 26, 1943 SteinwedellDec. 7, 1943 Claffey Oct. 16, 1945 Cummings Aug. 1, 1950 Shaplegh Oct.10, 1950 Shapleigh Oct. 10, 1950 Lewis Aug. 19, 1952 FOREIGN PATENTSGreat Britain of 1905 OTHER REFERENCES Handbook of Chemistry andPhysics, 27th ed., page 20 1703, Chemical Rubber Pub. Co., Cleveland,1943.

1. THE METHOD OF PRODUCING FUEL GASES FROM LIQUID CARBONACEOUSHYDROCARBON MIXTURES, WHICH COMPRISES THE STEPS OF SUBJECTING THE LIQUIDTO A CRACKING PROCESS BY INJECTING IT AT A CONTROLLED RATE AND AT AFIXED POINT CENTRALLY LOCATED IN A PARTICULATE BODY OF HARD HEMATITEMAINTAINED AT A TEMPERATURE ABOVE 1450 DEG. F AND SUBSEQUENTLYSUBJECTING THE PRODUCTS OF THE SAID CRACKING PROCESS TO THE ACTION OFGASEOUS OXIDIZING AGENTS SIMULTANEOUSLY INJECTED INTO THE BODY OFJEMATITE AT POINTS DOWN STREAM FROM THE POINT OF INJECTION OF THECARBONACEOUS LIQUID, THEREBY PRODUCING A COMBUSTIBLE MIXTURE OF FIXEDGASES HAVING A HIGHER HEATING VALUE THAN THAT OF HYDROGEN, CARBONMONOXIDE AND MIXTURES THEREOF.